Isothermal-adiabatic catalytic hydrocarbon conversion



April 7, 1964 E. v. BERGSTROM ETAL 3,128,242

ISOTHERMAL-ADIABATIC CATALYTIC HYDROCARBON CONVERSION 7 Sheets-Sheet 1 Filed June 8, 1961 April 7, 1964 E. v. BERGSTROM ETAL l 3,128,242

IsoTHERMAL-ADIABATIC cATALYTc HYDRocARBoN CONVERSION Er/c I/ @ergs/rom Rber/ J D V//n 5y gent @April 7, 1964 E. v. BERGSTROM ETAL 3,128,242

IsoTHERMAL-ADIABATIC CATALYTIC HYDRocARBoN CONVERSION Filed June 8, 1961 v Sheets-sheet :s

CHAR E 50, NAPHTHA April 7, 1964 E. v. BERGsTRoM ETAL 3,128,242

IsoTHERMALfADIABATIC CATALYTIC HYnRocARBoN CONVERSION Filed June 8, 196,1 7 SheetS--Sheet 4' la! SY////////////// E, v. BERGSTROM ETAL 3,128,242

IsoTHx-:RMAL-ADIABATIC CATALYTIQ HYDRocARBoN CONVERSION April?, 1964 7 Sheets-Sheet 6 Filed June 8, 1961 uw ma E. v. BERGSTROM ETAL 3,128,242

IsoTHERMAL-ADIABATIC cATALYTIc HYDROCARBON CONVERSION April 7, 1964 '7 Sheets-Sheet 7 Filled June 8. 1961 /m/en/ors Ef/'C 1./ Bergsf/Qm Raben* Dev/f7 Age/W United States Patent 3,125,242 'ISTHERMAL-ADIABATEC CTALY'HC HYDRGCARBGN CNVERSION Eric V. Bergstrom, Byrain, Conn., and Robert J. Devlin,

Iselin Township, Woodbridge County, NJ., assignors to Socony Mobil @il Company, luc., .a corporation of New York Filed June 8, 1961, Ser. No. M5645 21 Claims. (Cl. 208-65) yof mixtures of hydrocarbons boiling above the naphtha range, eg., gas oil, and catalytic cracking of normally liquid hydrocarbons boiling in the naphtha range. -Illustrative of catalytic hydrocarbon conversions which are essentially endothermic reactions is the reforming of naphthas. Among the essentially exothermic hydrocarbon conversions for which the present invention has particular potential are, hydrogenation, hydrodecontamination, and the like of hydrocarbon mixtures such as catalytically cracked naphthas, kerosines, domestic fuel oils, jet fuels, and the like.

Typical of the essentially endothcrmic hydrocarbon conversions is that of reforming straight run, catalytically cracked, and thermally cracked, naphthas or mixtures of two or more of the foregoing naphthas to convert the naphthenes to aromatics Iand the paraiiins to aromatics. The predominant reaction in the early stages of the latter conversion is dehydrogenation of the naphthenes to aromatics. Dehydrogenation is an endothcrmic reaction. `On the other hand, in the later stages of reforming hydrocracking is sufficiently important that the net result of the competing reactions is a slight rise in reaction ternperature. That is to say, the net reaction is slightly exothermic.

In contrast, hydrogenation of olefins to paratlins, of aromatics to naphthenes, of sulfur, nitrogen and other heterocyclic hydrocarbons to form a hydrogen derivative of the heteroeyclic atom and a saturated hydrocarbon is essentially exothermic. For example, in the hydrodesulfurfization of straight run naphtha the temperature orf the eiluent of a static bed reactor has been found to be as much as twenty-tive degrees Fahrenheit higher than the temperature of the reactant vapors at the inlet to the reactor.

Basically, -whether the hydrocarbon conversion be endothermic or exothermic the ideal condition is one of isothermicity. That is to say, it is recognized that, when the temperature of a reactant remains substantially constant at or alborut the optimum temperature for the reaction, improved results are obtained. However, previously designed isothermal reactors have utilized complex internals costly to install and to maintain.

IFurthermore, the endothermicity or exotherrnicity of a hydrocarbon conversion lvaries with the progress of the conversion. Thus, in reforming straight run naphthas under adiabatic conditions the change in temperature can be as much as 140 F. in the iirst ten percent of the catalyst and only about F. in the next forty-live percent and only about 6 to 9 F. in the last forty-tive percent of the catalyst. In other words, it is advantageous ICC to carry out the first stage of the reforming conversion under isothermal conditions rather than adiabtic conditions since the temperature variation from the optimum is not as great under isothermal conditions as when the iirst stage of the conversion is under adiabatic conditions.

This makes it necessary to distinguish between the classical definition of isothermal and the industrial definition of isothermal. Classically or theoretically under isothermal conditions the temperature in a reaction zone is substantially constant from the inlet to the outlet. lndustrially such a substantially constant temperature from inlet to outlet cannot be achieved especially in operations in which, for example, one hundred thousand pounds of reactant are treated. Consequently, quasi, 0r pseudoisothermal conditions in which the dilference between the temperature of the reactor vapor inlet and the temperature of the reactor vapor effluent is about 20 to 50 F. are considered as isothermal reactions although the actual temperature of the reactants fluctuates as much as 10 to 20 F. within the reaction zone. The present invention provides for the use of such quasior pseudoisothermal conditions employing reactors producing such quasior pseudo-isothermal reaction conditions. The reactors producing such quasior pseudo-isothermal reaction conditions are designated, in accordance with general practice in the industry, isothermal reactors. Consequently, the term, isothermal reactor, as used hereinbefore and hereinafter, is to be understood to designate a reactor in which the ydiierence between the temperature of the reactant vapors at the reactor vapor inlet and the temperature of vaporous reactant effluent is not more than about 50 F. and preferably is not more than about 10 F. and the temperature of the reactants Varies within the reactor in a sawtooth manner by not more than about 50 F., preferably not more than about 10 F. from the temperature of the reactant vapors at the reactor vapor inlet.

A hydrocarbon conversion unit comprises a plurality of hydrocarbon conversion cells. The hydrocarbon conversion unit of the present invention is piped for parallel flow of reactant through a plurality of hydrocarbon conversion cells on-stream while the catalyst in a-n olf-stream, swing, hydrocarbon conversion cell is being regenerated in any suitable manner. The hydrocarbon conversion cell comprises an isothermal reaction zone or reactor having at least one static bed of hydrocarbon conversion catalyst therein and at least 'one adiabatic reaction zone or reactor operated in accordance with static bed, or moving bed, Dr llui'dized bed, technique.

For the purpose of illustrating the application of the present novel isothermal-adiabatic method of catalytic hydrocarbon conversion, the reforming of naphtha containing not more than innocuous concentrations of sulfur, nitrogen and arsenic has been selected. An innocuous amount of sulfur is that amount of sulfur which when converted into hydrogen sulde does not cause undue corrosion of metal surfaces with which the hydrogen sulfide-containing gas is in contact and is dependent upon the ferrous alloy employed in fabricating the reforming unit. When ernploying platinum-group metal reforming catalyst an innocuous concentration of nitrogen is not more than l ppm, (part per million) of nitrogen in the feed. Preferably the reformer feed is essentially free from arsenic. However, an innocuous concentration of arsenic is that concentration of arsenic which, when the reformer feed is contacted with a bed of reforming catalyst comprising 0.35 percent platium by weight on alumina support, is insulicient to deactivate said catalyst within the life of the catalyst, for example, two years, as determined by other factors such as the temperature required to produce a reforinate having an octane rating of at least (R4-3 fil cc. TEL), the yield of reformate, and the mechanical strength of the catalyst.

The present isothermal-adiabatic method of catalyst hydrocarbon conversion as illustrated by the reforming of naphtha will be readily understood by those skilled in the art from the following description taken in conjunction with the drawings in which:

FIGURE l is a highly schematic ilowsheet illustrating the reforming of naphtha in an isothermal-adiabatic hydrocarbon catalystic conversion unit comprising four cells piped for parallel flow of reactant in which each cell comprises an isothermal iirst reactor and at least one adiabatic reactor, each cell being piped for series flow of reactant. A common liquid-gas separator, and a common fractionator is also provided;

For simplicity, the flow of heat transfer material from the heat transfer material heater to and through the isothermal reactors illustrated in FIGURE l and back to the heat transfer material (HTM) heater is diagrammatically illustrated in FIGURE 2;

FIGURE 3 is a highly schematic flowsheet of a unit for reforming naphtha comprising a plurality of isothermal reactors piped for parallel flow of reactants through the isothermal reactor(s) on-stream and a single adiabatic reactor operated in accordance with moving bed technique to which flow the eiuents of all of the isothermal reactors on-strearn without substantial reheat- FIGURE 4 is a vertical section of an isothermal reactor wherein a plurality of reaction tubes are heated by heat transfer material (HTM) iiowing upwardly at relatively high velocity through the annulus formed between the outer periphery of the reaction tube and the inner periphery of the associated HTM jacket;

FIGURE 5 is an enlarged view of a vertical section of one of the assemblies comprising a reaction tube and the associated HTM jacket showing details of the assembly of the head of the reaction tube, the associated HTM jacket, and the header of the reactor;

FIGURE 6 is a vertical section of a presently preferred isothermal reactor wherein a plurality of reaction tubes are radiantly heated to provide substantially isothermal reaction conditions in each reaction tube;

FIGURE 7 is a vertical section of a form of reaction tube and catalyst cartridge train comprising a head cata-- lyst cartridge, a plurality of intermediate catalyst cartridges, and a tail catalyst cartridge. Each catalyst cartridge comprises a plurality of annular catalyst beds. Each catalyst cartridge is constructed and arranged for passing fluid reactant alternately through the annular catalyst bed from the outer periphery thereof to the central conduit. The tail catalyst cartridge is movably mounted on a plurality of legs rigidly mounted on a plate rigidly mounted on a frustro-conical plug being a part of the reaction tube closure means;

FIGURE 7A is a vertical section of a similar reaction tube assembly differing primarily in the manner in which the tail catalyst cartridge is supported in the reaction tube. This construction provides for movably mounting the tail cartridge on a plurality of legs rigidly mounted on a shoulder. (Similar parts in drawings 7 and 7A have the same indices); and

FIGURE 8 is a vertical section of a presently preferred form of reaction tube and catalyst cartridge train comprising a head cartridge, a plurality of intermediate cartridges, and a tail cartridge. Each cartridge comprises a plurality of annular catalyst beds and means for passing iluid reactant alternately through the annular catalyst beds from the inner periphery to the outer periphery thereof.

The fundamental features of the present invention will be recognized by those skilled in the art from the followlow description taken in conjunction with the afore-enumerated drawings.

Many hydrocarbon conversions involve endothermic reactions and exothermic reactions. Thus, as presently practiced, reforming of straight run naphtha containing little, if any, olens results in a iirst endothermic stage during which practically all of the naphthenes in the straight run gasoline are dehydrogenated to aromatics and a second stage in which the parafi'lns originally present are hydrocracled and to some extent dehydrogenated and isomerized dependent upon the reaction pressure.

Attempts have been made to make the first stage thermally neutral by admixing olefin-containing naphtha with straight run naphtha in proportions such that the exothermicity of the hydrogenation of the olens in the one naphtha will balance the endothermicity of the dehydrogenation of the naphthenes in the straight run naphtha.

In general, when reforming naphtha the present invention provides for introducing a naphthene-containing naphtha into a plurality of isothermal reaction zones or reactors of sufficient capacity that the endothermic reaction of the dehydrogenation of naphthenes in the feed naphtha is substantially complete, i.e., at least to 85 percent of the naphthenes in the feed naphtha is converted to aromatics, by the time the charge naphtha reaches the outlet of the isothermal reactor. The etiiuents of the isothermal reactors are then introduced, with or Without reheating, into at least one adiabatic reactor. Preferably, there is at least one adiabatic reactor for each isothermal reactor. In the adiabatic reactors the exothermic conversion of paraflins to aromatics, iso-paraiiins, and hydrocarbons boiling below the boiling range of gasoline takes place to the extent necessary to provide a (l5-{- reformate having the required octane rating, i.e., reasearch octane, after the addition of three cubic centimeters of tetraethyl lead or tetramethyl lead or a mixture of lead alkyls.

The reactors can be under high pressure or low pressure. That is to say, the isothermal reactors can 'oe under a pressure of about 50 to 1200 p.s.i.g. and the adiabatic reactors under the same pressure less pressure drop due only to intervening equipment such as piping, heat exchanger and the like. On the other hand, the isothermal reactors can be under a reforming pressure of 5G() p.s.i.g. or more While the adiabatic reactors can be under a pressure substantially less than 590 p.s.i.g., e.g., 200 to 400 p.s.i.g.

It is presently preferred to employ static beds of reforming catalyst not only in the isothermal reactors but also in the adiabatic reactors. However, it is also within the scope of the present invention to use the xed bed isothermal reactors of the present invention in conjunction with a single adiabatic reactor or an adiabatic reactor with `each isothermal reactor and employing moving bed or i'luidized bed techniques in the adiabatic reactor(s).

It is presently preferred to use particle-form platinumgroup metal reforming catalyst having substantially the same composition in both the isothermal reactors and the adiabatic reactor(s). However, platinum-group metal reforming catalyst having a low acidity can be used in the isothermal reactors for the dehydrogenation of naphthenes while platinum-group metal reforming catalyst having a relative high acidity is used in the adiabatic reactor(s) for the conversion of the low octane normal paraiiins to high octane iso-parans and/ or aromatics and the hydrocracking concomitant with the production of C5-ireformate of the target octane rating. Similarly, non-noble metal reforming catalysts such as chromia-alumina, i.e., a mixture of oxides of chromium and aluminum; molybdenaalumina, i.e., a mixture of oxides of molybdenum and aluminum; or in general, a mixture of one or more oxides of metals of group VI, left column, of the periodic table and one or more refractory oxides such as oxides of aluminum, zirconium, magnesium can be employed in the adiabatic reactors while a platinum-group metal reforming catalyst is employed in the isothermal reactors.

Since platinum-group metal reforming catalysts are deactivated by reversible or irreversible poisons such as nitrogen and arsenic faster than by the deposition of coke, it is important that the feed naphtha be treated, if necessary, to reduce the concentrations of these platinum-group metal t3 reforming catalyst poisons to a satisfactory innocuous concentration. It has been found that when the naphtha with which a platinum-group metal reforming catalyst is contacted contains not more than one part per million (1 yp.p.m.) of nitrogen the deactivation of the catalyst is no more rapid than than that due to the deposition of coke. Nitrogen is a reversible catalyst poison. That is to say, a catalyst poisoned with nitrogen can be regenerated by the procedures usually employed for regeneration of platinumgroup metal reforming catalysts deactivated by the deposition of a carbonaceous deposit generally designated coke. On the other hand, arsenic is an irreversible platinumgroup metal reforming catalyst poison. Accordingly, it is preferred that the charge naphtha be esentially free from arsenic. That is to say, essentially free from arsenic designates a concentration of arsenic in a reformer feed which, when said reformer feed is contacted with a bed of reforming catalyst comprising 0.35 percent by Weight of platinum, is insufficient to deactivate said catalyst Within the life of the catalyst, for example two years, as determined by other factors such as the temperature required to produce a reformate having an octane rating (research-P3 cc. TEL) of at least 100, the yield of reformate, and the mechanical strength of the catalyst.

The concentration of sulfur which can be tolerated, i.e., the innocuous concentration of sulfur, is dependent primarily upon the corrosion resistance of the metals from which the various items of equipment have been fabricated. For example, when all piping, reactor liners, etc. have been fabricated from austenitic stainless steels the sulfur content of the naphtha feed can be as high as 1 percent hydrogen sulfide. On the other hand, when the piping, reactor liners, etc. have been fabricated of loW carbon steel the sulfur content of the naphtha feed to the reforming unit should not exceed about 0.02 percent hydrogen sulfide. A preferred method of reforming charge naphtha containing about 24 to about 70 percent by volume of naphthenes and the balance predominantly parafiins containing innocuous concentrations of nitrogen, sulfur, and arsenic, e.g., not more than 1 ppm. of nitrogen, not more than 2 l0*9 parts of arsenic, and preferably not more than 200 p.p.m. of sulfur, is ilustrated in a highly schematic manner in FIGURE l while the flow of heat transfer medium for the isothermal reactors is illustrated in FIGURE 2.

The spatial relation of the reforming cells, i.e., an isothermal reactor and associated adiabatic reactor, simplifies the piping required to regenerate the catalyst in one cell or one reactor While reforming naphtha in the other cells of the reforming unit. While a unit having four cells is illustrated in FIGURES 1 and 2, those skilled in the art will understand that a greater number or fewer cells can be employed. It is also manifest that when employing moving bed or fluidized techniques in the adiabatic reactors the four adiabatic static bed reactors can be replaced by a single adiabatic reactor.

In general, reforming conditions of temperature, pressure, liquid hourly space velocity, and hydrogen-tonaphtha mol ratio are maintained in the isothermal reactors within the following ranges:

Isothermal Reactors 1 Dependent upon the target octane of the 05+ reformate.

Fixed Bed l Adz'abatc Reactor Broad i Preferred Catalyst:

Percent Platinum-group metal by 0.1 to 10 0.35 to 2.0.

Wt. Percent Halogen 0.1 to 8 0.35 to 0.7. Support Refractory Alumina.

Oxide. Temperature, F 800 1 to 1,000 850 to 980. Pressure, p.s.i.g 50 to l,200 200 to 450. Liquid Hourly Space Velocity, v./hr./V 0 5 to 10. 1 to 3. Hydrogen-to-naphtha mol ratio 1 to 20... 4 to 10 1 Dependent upon the target octane ofthe 05+ reformate.

In general, the reaction conditions of temperature, pressure liquid hourly space velocity, and hydrogen-tonaphtha mol ratio are those Well known to thoseskilled in the art and dependent upon the catalyst employed, the activity thereof, and the target octane of the leaded gasoline produced from the C5-1- reformate.

It is presently preferred to employ a fixed bed isothermal reactor and a fixed bed adiabatic reactor piped for serial flow of reactants in each cell of the reforming unit. Accordingly, FIGURES 1 and 2 illustrate in a highly diagrammatic manner the flow of reactants (FIG- URE l) and the flow of heat transfer medium (HTM) (FIGURE 2). Thus, in FIGURE l a charge naphtha having innocuous concentrations (as defined hereinbefore) of sulfur, nitrogen, and arsenic is pumped from a source not shown through pipe 1 by pump 2. Pump 2 discharges the charge naphtha into pipe 3 at a pressure in excess of the pressure in the reactors on-stream. For the purpose of this description reactors 2% and 30 are considered to be off-stream or under regeneration conditions. Consequently, for the purpose of this description cells I, II, and IV, i.e., reactors 25 and 26, 27 and 28, and 31 and 32, are onstream.

The charge naphtha flows through pipe 3 to indirect heat exchanger 4 Where the charge naphtha is heated by indirect heat exchange with the total eiiiuent of reactors 26, 28, and 32 flowing from heat exchanger 6 through conduit 7. From indirect heat exchanger 4 the charge naphtha flows through pipe 5 to indirect heat exchanger 6 Where the charge naphtha is heated further by indirect heat exchange with the total eliiuent of the reactors 0nstream, to Wit: the adiabatic reactors of cells I, II, and IV (reactors 26, 28 and 32, respectively), flowing through conduit 45. From indirect heat exchanger 6 the charge naphtha flows through pipe 8 to coil 9 in naphtha furnace or heater 10. Preferably, a small portion of hydrogencontaining recycle gas, say about 5 to about l5 percent, flowing from liquid-gas separator 51 to compressor 53 through conduit 52 and thence through conduit 56 to recycle gas heater or furnace 1.2 ows through conduit 73 under control of valve '74 to pipe 8 Where this portion of the hydrogen-containing recycle gas is mixed with the charge naphtha. The balance of the recycle gas flowing through conduit 56 flows to coil 11 in recycle gas furnace or heater 12. The charge naphtha is heated in furnace 11.0 and the recycle gas is heated in heater 12 to temperature such that when mixed in the ratio of l to 20 mols of hydrogen to 1 mol of charge naphtha the resulting charge mixture has a temperature to provide a vapor inlet reforming temperature in the range set forth hereinbefore. To avoid thermal cracking of the naphtha the naphtha usually is not heated to a temperature in excess of about 960 F. while the recycle gas is heated to the temperature necessary to provide the charge mixture temperature required to provide the required dehydrogenation of naphthenes to produce the target octane of the leaded gasoline. Thus, for example, when producing octane leaded gasoline employing fresh reforming catalyst comprising 0.6 percent by Weight platinum, 0.7 percent by weight chlorine on an alumina support and a hydrogen-to-naphtha mol ratio of 1 to 20 and a recycle gas mol ratio of 1.5 to 35 the charge naphtha is heated to 850-900 F. and

7 the recycle gas is heated to 925 to ll00 F. to provide a charge mixture temperature of 910 to 950 F.

The heated charge naphtha flows from coil 9 through conduit 13 to conduit 14. The heated recycle gas iiows through conduit l to conduit 14. ln conduit lift the heated recycle gas and the heated naphtha mix to form a charge mixture having the required vapor inlet reforming reaction temperature.

From conduit )i4 the charge mixture ows in parallel in substantially equal Volume to reactors 25, 27, and 3l through conduit ll7, 19, and 23 respectively under control of valves 1S, 20, and 24 (valve 22 being closed. Valves 79 and S0; 82 and 85; 85 and 86 also being closed).

In reactors 25, 27, and 3l the charge mixture is contacted with particle-form solid reforming catalyst, preferably platinum-group metal reforming catalyst, and especially platinum-metal reforming catalyst such as described hereinbefore, under reforming conditions of temperature, hydrogen-to-naphtha mol ratio, and liquid hourly space velocity dependent upon the activity of the catalyst and the target octane to dehydrogenate at least a portion, and preferably at least 80 to 85 percent, of the naphthenes in the charge naphtha under substantially isothermal conditions. That is to say, the difference between the temperature of the effluent and the vapor inlet temperature of each isothermal reactor is not more than 50 F.

The effluent of isothermal reactor 25 flows through conduit 33 to adiabatic reactor 26. The eluent of isothermal reactor 27 ilows through conduit 34 to adiabatic reactor 2S. The eiuent of isothermal reactor 3]. iiows through conduit 36 to adiabatic reactor 32. In each of the adiabatic reactors the eluent of the associated isothermal reactor is contacted with that amount of particle-form reforming catalyst required to raise the octane ratings of the gasoline hydrocarbons of the isothermal reactor e'fuents to provide a total adiabatic eluent the gasoline hydrocarbons of which have the target octane rating.

Thus, for example, the effluents of isothermal reactors 25, 27, and 3l can have a temperature of 980 F. The eluent of each isothermal reactor is then contacted Without reheating with about 50 to about 100 barrels of fresh platinum-group metal catalyst containing 0.6 percent by weight platinum and 0.7 percent by weight chlorine on alumina support to produce a C54- reformate from which a RVP leaded gasoline having an octane rating (research-|-3 cc. TEL) of 100 can be produced. On the other hand, the charge mixture can be contacted under substantially isothermal conditions in reactors 25, 27, and 31 at a temperature of about 950 F. and the isothermal efiluents reheated to 980 F before being introduced into adiabatic reactors 26, 28, and 32. Furthermore, the charge mixture can be contacted under substantially isothermal conditions at a temperature of 980 F. in isothermal reactors 25, 27, and 3l, the isothermal eluents cooled by heat exchange with charge naphtha, for example, and the isothermal effluents contacted with reforming catalyst in adiabatic reactors 26, 28, and 32 at reforming temperatures, for example of 930 to 4960 F., i.e., 20 to 50 F. below the temperature of the isothermal eflluents.

From adiabatic reactor 26 the effluent thereof flows through conduit 37 under control of valve 3S to conduit 45. From adiabatic reactor 28 the eluent thereof ilows through conduit 39 under control of valve 40 to conduit 45. From adiabatic reactor 32 the efuent flows through conduit 43 under control of valve 44 to conduit 45. (Valves 42, 8S and S9, 91 and 92, and 94 and 95 being closed.)

The mixed adiabatic reactor etlluents ilow through conduit 45, indirect heat exchanger 6, conduit 7, and indirect heat exchanger 4 to conduit 46. The mixed adiabatic effluents flow through conduit 46 to cooler 47. From time to time or continuously a portion of the mixed adiabatic eiiluents are diverted through conduit 43 under control of valve 49 so that the mixture of efuents lowing through conduit 50 has a temperature at which under the existing pressure C4 and heavier hydrocarbons are condensed While hydrogen and substantially all of the C3 and lighter hydrocarbons are uncondensed.

In liquid-gas separator 51 the condensed hydrocarbons are separated from the uncondensed reformer gas comprising hydrogen and C1 to C3 hydrocarbons. The Ieformer gas ilows from separator 51 through conduit 52 to recycle gas compressor 53. A portion of the reformer gas, usually about equal in volume to the net make of gas in the reforming reactions, is diverted through conduit 54 under control of valve 55 to other processes, such as hydrodccontamination of the reformer feed, hydrogenation of fuel fractions, hydrogenation of lubricating oil fractions, hydrocracking of gas oil fractions, and the like in which hydrogen-containing gas of reformer gas composition can be used.

The balance of the reformer gas suicient to provide the desired hydrogen-to-naphtha mol ratio in the reforming reactors and designated recycle gas is recompressed to a pressure sutliciently higher than the pressure in reactors ori-stream that the recycle gas flows through conduit 56 to coil itl in recycle gas heater l2.

The condensed C4 and heavier hydrocarbons ilow from separator 5l through pipe 57 to indirect heat exchanger 58 where by indirect heat exchange with the fractionator bottoms flowing from indirect heat exchanger 59 through pipe 6@ the condensate is heated. The condensate fiows from indirect heat exchanger 58 through pipe 6l. to indirect heat exchanger 59 where through indirect heat exchange with the bottoms of fractionator 63 flowing therefrom through pipe 73 the condensate is heated to a temperature at which C4 and lighter hydrocarbons are Volatilized. From heat exchanger 59 the heated condensate idows through pipe 62 to fractionator 63.

An overhead comprising C4 and lighter hydrocarbons is taken through conduit 64 and cooled in condenser 65 to a temperature at which C., and heavier hydrocarbons are condensed. The cooled overhead ilows from condenser 65 through conduit 66 to accumulator 67. The C3 and lighter hydrocarbons flow from accumulator 67 through conduit 68 to the refinery fuel main while the C4 and heavier hydrocarbons flow from accumulator 67 through pipe 69 to recovery as light naphtha. A portion of the C4 and heavier hydrocarbons is drawn from pipe 69 through pipe 70 by pump 7l and discharged into pipe 72. From pump 7l the C., and heavier hydrocarbons flow through pipe 72 to fractionator 63 for use as reux therein.

The bottoms of fractionator 63 comprising C5 and heavier hydrocarbons iiows from fractionator 63 through pipe 73 to indirect heat exchanger 59. From indirect heat exchanger 59 the bottoms flows through pipe 6d to indirect heat exchanger 5d. From indirect heat exchanger 58 the bottoms flows through pipe 74 to cooler 75 where the bottoms is cooled to a temperature at which the lowest boiling hydrocarbons constituent of the bottoms is liquid. From cooler 75 the liquid bottoms liows through pipe 76 to storage, and/or the addition of additives, and/or blending.

As was noted hereinbefore, for the purpose of illustration it is assumed in the foregoing description of the present method of reforming that the catalyst in cell lll is being regenerated. Accordingly, the regeneration of the catalyst in cell III Will be described as illustrative of the regeneration of catalyst, in any other cell of the reforming unit. In general, the blocking valves between the inert gas main 77 and the cells ori-stream are closed whereas the blocking valves between the inert gas main 77 and the cell in which the catalyst to be regenerated is disposed are open. Thus, valves 109 and 110 in by-pass line lll are open. Similarly, the blocking valves between the cells on-stream and the regeneration products main 73 are closed whereas the blocking valves between the cell under regeneration conditions and the regeneration products main 78 are open. Thus, since cell lll or reactors 2.9

'd and 30 is under regeneration conditions blocking valves 79 and S0 in by-pass pipe 81, valves d2 and 83 in by-pass pipe 84, and valves 85 and 86 in by-pass pipe 87 are closed.

Similarly, valves 38 and S9 in by-pass line 90, valves 91 and 92 in by-pass line 93, and valves 94 and 95 in bypass line 96 also are closed. However, the blocking valves 97 and 98 in by-pass line 99 connecting reactor 30 with the regeneration products main 78 are open (valves 101, 102, 103, 104, 105 106, 107, and 10S are vent valves through which any gases leaking past the associated blocking valves 110W to suitable mains. Thus, valves 101, 102, 104, 105', 107, and 10S are open to prevent hydrocarbon gases leaking past the associated blocking valves mixing with either the regenerating gas or the regeneration products. On the other hand, vent valves 103 and 106 are closed).

With the blocking valves set as described hereinbefore inert gas, preferably flue gas containing not more than 0.2 to 1.5 percent oxygen by volume produced in an inert gas generator (not shown) flows from the aforesaid inert gas generator through regenerating gas main 77. While it is preferred presently to produce inert gas by burning carbonaceous fuel such as a fraction of petroleum under conditions such that there is no substantial excess of oxygen and the ue gas produced contains not more than 0.2-1.5 percent oxygen by volume, nitrogen or other inert gas can be used.

When the catalyst in a reforming cell, for example cell III comprising isothermal reactor 29 and adiabatic reactor 30 is to be regenerated valves 22 and 42 are closed, valves 109 and 110 and 97 and 93 opened (valves 106 and 103 being closed) and the cell evacuated through conduits 99 and 78 to about 25 inches of mercury vacuum. Valves 109 and 110 are opened and the cell purged with inert gas flowing from regenerating gas main 77 through by-pass pipe 111, to and through isothermal reactor 29, conduit 35, adiabatic reactor 30, conduit i1 (valve 42 closed), by-pass pipe 99 and regeneration products main 7S until the oxygen Content of the purge gas is less than 2 mol percent. The carbonaceous deposit on the catalyst in the cell is then burned ofrr by heating the inert gas to a temperature of about 700 to 800 F. After the temperature in the bed(s) of catalyst to be regenerated has reached 700 to 800 F. gas containing free oxygen, for example, air, is mixed with the circulating inert gas to provide a mixture containing initially about 0.2 percent by volume of oxygen and increasing the oxygen concentration incrementally to about 5 percent. The carbonaceous deposit is burned off the catalyst at temperatures at which the catalyst is not irreversibly deactivated dependent upon the moisture content of the circulating gas. The cell under regeneration is evacuated, purged with inert gas, pressured with hydrogen-containing gas, and put back on-stream. (For a more detailed description of methods of regenerating platinum-group metal reforming catalysts those skilled in the art are referred to co-pending applications for United States Letters Patent Serial No. 764,556, tiled October 1, 1958, in the name of George A. Engelland and Serial No. 45,827 (series of 1960), led July 28, 1960, led in the name of Leon Capsuto). Those skilled in the art will understand that While the catalyst in cell III is being regenerated naphtha is being reformed in cells I, 1I, and IV.

Those skilled in the art Will understand that the method of reforming naphthas including straight run naphthas containing 20 to 70 percent by volume of naphthenes and the balance primarily parafns and cracked naphthas, i.e., catalytically and/ or thermally cracked naphthas, comprises contacting a naphtha containing not more than innocuous concentrations of sulfur, nitrogen, and arsenic with particle-form solid reforming catalyst in an isothermal reactor under reforming conditions of temperature, pressure, liquid hourly spaced velocity and hydrogen-to- 10 naphtha mol ratio to dehydrogenate a major portion, preferably about to about 85 percent of the naphthenes originally present in the charge naphtha. The efliuent of the isothermal reactor with or Without heat exchange is then contacted with particle-form solid reforming catalyst in at least one adiabatic reactor under reforming conditions of temperature, pressure, liquid hourly space velocity, and hydrogen-to-naphtha mol ratio to produce a C54- reformate from which 10 RVP leaded gasoline having the target octane rating can be produced by pressuring with butane and the addition of anti-knock additive. It is preferred that the reforming catalyst in all reactors be platinum-group metal reforming catalyst. However, a non-noble metal reforming catalyst can be used in either or both the isothermal reactors and the adiabatic reactors.

It is also emphasized that the reforming unit is comprised of a plurality of reforming cells. Preferably each cell comprises an isothermal reactor having a static bed of particle-form solid reforming catalyst and at least one adiabatic reactor having a static bed of particle-form soiid reforming catalyst. However, the individual adiabatic reactors each having a static bed of particle-form solid reforming catalyst can be replaced by a single adiabatic reactor operated in accordance with moving bed or fluidized bed technique.

It will be observed that in the present method of reforming the flow of reactants is in parallel through the plurality of cells ori-stream. This provides the advantages (1) that the isothermal reactors are each smaller than required to treat the same volume of feed employing one isothermal reactor (the smaller isothermal reactors provide many advantages from both a capital cost standpoint, a maintenance standpoint and a temperature control standpoint), and (2) the piping to supply fluid reactants to a yplurality of cells in parallel ow is much less complicated and generally smaller in size than in a unit Where the flow of fluid reactants is in series with a swing reactor which must be cut-in and cut-out as the condition of the catalyst in each reactor requires. Thus, for example, to cut-out one cell and cut-in another cell requires the closing of four main valves and the opening of four main Valves Whereas when the reactors are in series as in the prior art methods at least eight main valves are closed and at least eight main valves are opened.

The isothermal reactors can be of any suitable design. Thus, for example, as illustrated in FIGURES 1, 2, and 3 the isothermal reactors are designed for the use of liquid heat transfer medium to maintain the difference in temperature between the vapor inlet and the vapor outlet to a minimum and not greater than about 20 to about 50 F. On the other hand, the isothermal reactor can employ radiant heat supplied, for example, for example, by a plurality of uid fuel burners which are controlled individually or in banks to regulate the amount of heat supplied to any portion of the tubes of the plurality of reaction tubes Within the furnace.

In the isothermal reactors employing liquid heat transfer medium such as a mixture of molten salts known to the art or organic liquids stable at the required temperature, it is preferred to pipe the isothermal reactors as illustrated in FIGURE 2 for the ilow of heat transfer medium from the HTM heater or furnace to the various isothermal reactors, then to a HTM storage tank, and back to the HTM heater or furnace.

Presently, it is preferred to employ the Well-known mixture of molten salts comprising nitrites and nitrates of sodium. The heat transfer medium, HTM fluid, is drawn from storage tank by pump 121 and discharged into pipe 122. The HTM fluid ows through pipe 122 to coil 123 in HTM heater or furnace 124i. In HTM heater 124 the HTM fluid is heated to a temperature such that the HTM iluid entering the isothermal reactors has a temperature about 65 to about 195 F. higher than the reaction temperature to be maintained in the reaction tubes. From HTM heater 124 the HTM fluid flows through pipe 125 to HTM manifold 126. The HTM fluid flows in parallel to the various isothermal reactors through HTM manifold branches 127, 128, 129, and 131) to the isothermal reactors 25, 27, 29, and 31 respectively. The HTM fluid flows from the isothermal reactors through pipes 131, 132, 1.33 and 134 respectively. Each isothermal reactor is provided with a liquid level control (LLC) 135, 135, 137, and 138 respectively of conventional design whereby the level of the HTM fluid in each isothermal reactor is regulated. Each liquid level control actuates a slave valve 139, 141i, 141, and 14.2 respectively. When the level of the HTM fluid in any isothermal reactor reaches the predetermined height the associated slave valve is actuated to open or to close, partially or completely, the slave valve thereby maintaining the level of the HTM fluid in the associated isothermal reactor. Flow of a portion of the outwardly flowing HTM fluid through the respective associated by-pass 143, 1414-, 145, and 14d is induced by the eductor nozzle shown more clearly in FIGURE 4. In this manner the HTM fluid is circulated at high velocity through the annular space between sleeve 176 (FIGURE 4) and the enclosed reaction tube 177 and discharged into the pool of HTM in the isothermal reactor to flow downwardly around the outer peripheries of the reaction tube sleeves to plate 17h (FTGURE 4) from which it llows through HTM outlets 131, 13?., 13.3, and 131i. respectively. Under the control of slave valves 139, 143, and 141 the HTM fluid flow through manifold branches 147, 14S, and 149 to HTM return manifold 151. Under control of the associated slave valve (142) HTM uid flows from the isothermal reactor nearest the HTM fluid storage tank through pipe 134i to pipe 156. The HTM fluid in HTM return manifold 151 flows into pipe 1519. The HTM fluid in pipe 15@ flows into HTM fluid storage tank 121B for recycle through the heater to the isothermal reactors.

The preferred type of isothermal reactor heated by means of HTM iiuid is illustrated in FIGURE 4.

A presently preferred embodiment of the present invention wherein the effluents of a plurality of isothermal reactors piped for parallel flow of fluid reactants through the isothermal reactors on-stream are combined and contacted with particle-form reforming catalyst in a single reactor operated in accordance with moving bed or luidized bed techniques is illustrated in FGURE 3. Those skilled in the art will recognize that for illustrative purposes the isothermal reactors have been depicted as of the same general type as those symbolized in FlG- URES 1 and 2. For simplicity of illustration the piping for regeneration of the catalyst in the isothermal reactors and the piping for the HTM fluid has been omitted. The reactor and kiln for reforming in accordance with moving bed technique is illustrated for operation of both the reactor and kiln at pressures of the order of l to 75 p.s.i.g. The illustration of reforming employing moving bed technique has also been simplified by omitting some heat exchangers. For more details of moving bed technique than are given hereinafter and for details of equipment and operation of the moving bed reactor at pressures of the order of 200 p.s.i.g. and greater while operating the kiln at atmospheric pressure reference is made to various issued patents, for example, US. Patents Nos. 2,763,598; 2,772,216; 2,870,083; and 2,886,516.

It is preferred to use platinum-group metal reforming catalyst in the isothermal reactors. For example, a particle-form solid reforming catalyst comprising 0.35 to 1.0 percent by weight of platinum on an alumina support can be employed. While a catalyst of the same class can be used in the adiabatic reactor, it is preferred to use a non-noble metal reforming catalyst such as particle-form chromia-oxide-alumina reforming catalyst comprising about 18 to about 30 percent by weight oxide of chromium and the balance aluminum oxide when employing moving bed technique.

The isothermal reactors as stated hereinbefore are employed under reforming conditions of temperature, pressure, liquid hourly space velocity, and hydrogen-tonaphtha mol ratio to provide a mixed isothermal etlluent in which a preponderant portion, preferably to 85 percent, of the naphthenes originally present in the charge naphtha have been converted to aromatic hydrocarbons. For overall liquid hourly space velocities of 0.5 to 5 the liquid hourly space velocities (v./hr./V.) in each of the isothermal reactors (three on-stream) will be of the order of 10 to 150.

As illustrated in FTGURE 3 a charge naphtha, i.e., straight run, catalytically cracked, thermally cracked, or a mixture of two or more of the foregoing classes of naphthas, containing innocuous concentrations (as defined hereinbefore) of nitrogen, arsenic, and sulfur is drawn from a source not shown through pipe 3% by pump 3111. Pump 381 discharges the naphtha into pipe 3192 at a pressure sutliciently higher than that in the isothermal reactors to compensate for pressure drop through the intervening equipment. Presently, it is preferred to operate the isothermal reactors at pressures of the order 500 to 750 p.s.i.g. The charge naphtha ows through pipe 382 to heat exchanger 344 where the charge naphtha is heated by indirect heat exchange with the effluent of the adiabatic reactor. From indirect heat exchanger 344 the charge naphtha flows through pipe 303 to coil 31M. in naphtha furnace or heater 305.

In naphtha furnace 3195 the charge naphtha is heated to a reforming temperature dependent upon the activity of the particle-form reforming catalyst in the isothermal reactors on-stream and the target octane. The charge naphtha is usually heated to a temperature of about 850 to about 900 F. but not higher than the temperature at which thermal reforming or cracking will have a noticeable effect upon the yield of (I5-ireformate (C5 and heavier reformate). Hydrogen-containing gas, usually reformer gas after start-up, flowing from liquidgas separator 355 through conduit 356 to compressor 3'll7 and thence, after recompression at least to substantially the pressure under which the charge naphtha flows from pump 361, through conduit 302, flows through conduit 338 to heat exchanger 342 where the reformer gas is heated by indirect heat exchange with the eflluent of the adiabatic reactor. From indirect heat exchanger 342 the hydrogen-containing gas, hereinafter designated recycle gas, ows through conduit 3119 to coil 310 in recycle gas furnace or heater 311.

In recycle gas heater 311 the recycle gas is heated to a temperature such that when mixed with the heated charge naphtha in the hydrogen-to-naphtha mol ratio of 1 to 20 the charge mixture has the vapor inlet reforming reaction temperature required by the activity of the catalyst to dehydrogenate a preponderant portion, preferably at least 80 to 85 percent of the naphthenes in the charge naphtha to aromatic hydrocarbons.

Ther heated charge naphtha flows from naphtha heater 395 through pipe 3116 to isothermal manifold 313. The heated recycle gas ows from recycle gas furnace 311 through conduit 312 to isothermal manifold 313 and is mixed therein with the heated charge naphtha to form a charge mixture having the required vapor inlet reforming reaction temperature.

For the purpose of the present illustration it will be assumed that the particle-form reforming catalyst in isothermal reactor 323 is being regenerated. Accordingly, valve 317 in isothermal manifold branch 316 and valve 329 in effluent manifold branch 328 are closed. Valves 315, 319, and 321 in isothermal manifold branches 314, 31S, and 321? respectively are open as are valves 327, 331, and 333 in eflluent manifold branches 326, 330, and 352 respectively.

The heated charge mixture ows from isothermal manifold in substantially equal portions through isothermal manifold branches 314, 318, and 320 into and through isothermal reactors 322, 324, and 325 respectively.

In the isothermal reactors a preponderant portion, preferably at least 8O to 85 percent, of the naphthenes are converted to aromatic hydrocarbons. The eiuent of the several isothermal reactors 322, 324, and 325 ow through etiluent manifold branches 326, 330, and 332 respectively to etiiuent manifold 334. From eiiluent manifold 334 the mixed isothermal effluents ow to conduit 335. When the isothermal reactors are operating at a pressure of the order of 500 p.s.i.g. or more and the adiabatic reactor is operating at a pressure considerably lower, say 300 or more p.s.i. lower, the pressure of the mixed isothermal ethuent is reduced to not less than that of the adiabatic reactor in any suitable manner as for example by a reducing valve or a turbine.

The mixed isothermal eflluent ows through conduit 335 to distributor 336 in the adiabatic reactor 35S. In general, even when the reaction temperature in the adiabatic reactor is higher than that of the mixed isothermal eiiiuents it is unnecessary to reheat the mixed isothermal eiiuent since the reaction temperature can usually be attained by regulation of the temperature of the regenerated catalyst flowing from the kiln 363 and the catalystto-oil ratio in reactor 353.

The reaction temperature in adiabatic reactor 358 is dependent upon the target octane rating of the reformate as measured by the octane rating of the leaded gasoline. In the adiabatic reactor the unconverted naphthenes, if any, are converted to aromatic hydrocarbons, and the parains of the charge naphtha are isomerized, hydroaromatized, and hydrocracked to the extent required to produce a C54- reformate of target octane rating. The reaction temperature in the adiabatic reactor is also dependent upon the activity of the regenerated catalyst. In general, the dependent variables are within the follow- The proportion in which the mixed isothermal eliluent flows upwardly and downwardly from distributor 336 is regulated by valves 333 and 34@ in etlluent conduits 337 and 339 respectively. As illustrated, distributor 336 is positioned at about the mid point of reactor 336 dividing the catalyst bed and the reactor into two beds or zones containing about equal volumes of catalyst. Accordingly, valves 338 and 340 are controlled to cause about fty percent of the mixed isothermal effluent to ow upwardly and the balance downwardly. The distribution of the mixed isothermal etfluent can be otherwise as taught in one or more of the issued United States patents enumerated hereinbefore.

From adiabatic reactor 358 the etiiuent of the upper zone U iows through conduit 337 under control of valve 338 to conduit 341. The eiifluent from the lower zone L Hows through conduit 339 under control of valve 340 to conduit 341. The mixed zone eluents flow through conduit 341 to indirect heat exchanger 342 where heat is transferred to the recycle gas. From heat exchanger 342 the mixed zone eiliuents flow through conduit 343 to indirect heat exchanger 344 where heat is transferred to the charge naphtha. From heat exchanger 344 the mixed zone eiluents flow through conduit 345 to cooler 346. In cooler 346 the mixed zone eiluents are cooled to a temperature at which under the existing pressure C4 and heavier hydrocarbons are condensed. From cooler 346 the cooled mixed eluents ilow through conduit 347 to liquid -gas separator 348. In liquid-gas separator 348 the uncondensed mixed zone efiiuents are separated from the condensate. The uncondensed adiabatic reactor eiiiuent ilows from separator 348 through conduit 349 to purnp 350 which discharges the 14 uncondensed adiabatic reactor eiiluent into conduit 351 through which the uncondensed adiabatic reactor effluent tlows to conduit 352.

The condensed adiabatic reactor eiiluent flows from separator 348 through conduit 352 and is mixed with the uncondensed adiabatic reactor eiliuent flowing from conduit 351. The condensed and uncondensed adiabatic reactor efuent ilows through conduit 352 to cooler 353 where the uncondensed and condensed adiabatic reactor eilluent is cooled to a temperature at which C4 and heavier hydrocarbons are condensed under the existing pressures. From cooler 353 the condensed and uncondensed adiabatic efuent iiows through conduit 354 to liquid-gas separator 355. In separator 355 the liquid C4 and heavier hydrocarbons separate from the uncondensed hydrogen and C1 to C3 hydrocarbons. The C4 and heavier hydrocarbons ilow from separator 355 through pipe 357 to iinishing including stabilizing, addition of additives such as anti-knock compounds, anti-icers, etc. From separator 355 the reformer gas comprising the hydrogen and C1 to C3 hydrocarbons of the adiabatic reactor eiuent iiows through conduit 356 to compressor 307. A portion of the reformer gas about equal to the net make of gas in the reactors is diverted through conduit 35S under control of Valve 359 to other processes, such as hydrodecontamination of the reformer feed, hydrogenation and hydrodecontamination of distillate fuel oils, hydrocracking of gas oils and the like in which hydrogen-containing gas of reformer gas composition can be used. The balance to provide the hydrogen required in the reforming reactors and designated recycle gas is compressed by compressor 3517 and ows to recycle gas heater 311 as described hereinbefore.

The iiow of catalyst through reactor 336 is as a compact column. Thus, hot active catalyst flows from hopper 363 into reactor 353. The hot active catalyst flows downwardly through the upper and lower zones of reactor 353 in contact with the isothermal efuent flowing from distributor 336. The at least partially inactivated catalyst flows from reactor 358 through conduit 359 to chute 360. The catalyst is discharged from chute 360 into means for lifting the catalyst to kiln hopper 362 such as a gas lift or an elevator 361. The catalyst is discharged from elevating means 361 into kiln hopper 362. From kiln hopper 362 the catalyst iiows into kiln 363 where the carbonaceous deposit is burned orf in a stream of combustion-supporting gas. The catalyst ilows downwardly through kiln 363 through conduit 364 and thence through chute 365 to catalyst elevating means 366. Catalyst elevating means 366 can be an elevator or a gas litt or the like. Catalyst elevating means 366 discharges the regenerated catalyst into chute 367 through which the regenerated catalyst flows to discharge into catalyst hopper 368.

The preferred form of isothermal reactor illustrated in FIGURES 1, 2, and 3 comprises a cylindrical container having a plurality of reaction tube-HTM jackets mounted therein as illustrated in FIGURES 4 and 5. (FIGURE 5 is an enlarged view of a vertical section of one of the reaction tube-HTM jacket assemblies.)

As illustrated in FIGURES 4 and 5 the required heat for the endothermic reaction is supplied in a liquid heat transfer medium (HTM) such as a molten mixture of inorganic salts, or an organic material having a boiling point above the temperature required to supply the heat for the endothermic reaction and having resistance to marked decomposition, i.e., is relatively stable, at the temperature employed.

The isothermal reactor comprises a cylindrical tank, fabricated from any suitable structural material which is relatively non-corrosive with respect to the HTM employed. The cylindrical tank has a bottom 161, preferably of generally elliptical shape, and a top 162. The cylindrical tank usually is provided with an outer layer of insulating material (not shown) to reduce heat losses. Tank 160 is provided with a HTM inlet 163 and a HTM outlet 164. Mounted in a suitable manner on HTM inlet 163 is a Venturi 165 having a nozzle 166 and an inlet for inducted HTM 167. A by-pass pipe 1611 is mounted in any suitable manner on HTM induct inlet 167 and connected with the tank HTM outlet 164 in any suitable manner. By-pass pipe 16S is provided with nipple 169 through which the HTM in excess of that recirculated by the Venturi 165 ows to the associated return manifold branch. Thus, 16S (FIGURE 4) corresponds to by-pass 143, 144, 145, and 146. Nipple 169 is connected with return manifold branches 147 or 143 or 149 or 150.

Rigidly mounted in any suitable manner on the inner periphery of tank 160 between HTM outlet 164 and HTM inlet 163 and preferably spaced a short distance above HTM inlet 163 is plate 170 provided with a plurality of openings in which the reaction tube-HTM jacket assemblies are mounted as hereinafter described.

Tank 160 is provided in the bottom 161 with a manway 171 which also serves as a HTM drain. Manway 171 is provided with closure means, for example, piate 172 movably mounted in a HTM-tight manner on manway 171. Plate 172 is provided with a port on which is mounted in any suitable HTM-tight manner pipe 173. A valve 174 is mounted in any suitable manner on pipe 173. Conduit means 175 is mounted connecting valve 174 with the HTM storage tank (not shown).

Each reaction tube-HTM jacket assembly comprises the HTM jacket tube 176 and reaction tube 177. Jacket tubes 176 are rigidly mounted in any suitable manner in the orifices provided therefore in plate 170. When desirable or necessary a stabilizing device, such as a spider of bars or a partial tube plate, or even a few buttons, for example, three, on the exterior periphery of the reaction tubes can be used for horizontal stabilization of the upper ends of the jacket tubes.

The top 162. of tank 160 is provided with a diaphragm return bend to compensate for expansion and contraction. A plurality of flanged nipples 178 (FIGURE 5) are mounted on top 162 in any suitable manner. A flanged header 179 is movably mounted as by means of bolts 180 and associated nuts 131 on flanged nipple 178. Reaction tube 177 is rolled into header 179 and supported thereby. Header 179 is provided with reactant inlet 182 to which is connected reactant inlet manifold branch 183. Reactant inlet manifold branch 183 is connected in any fluid-tight manner to reactant inlet manifold 134. Reactant inlet manifold 184 in turn is connected with the feed manifold branch associated with the isothermal reactor. For example, manifold 134 (FIGURE 4) is connected to feed manifold branch 17 or 19 or 21 or 23 (FIGURE l).

Header 179 is provided with a closure means 185 preferably of truncated cone shape which complements the interior periphery of the upper portion of header 179. Header 179 is also provided with a yoke 186 having legs 187. Yoke 186 is provided with a threaded orifice in which screw 188, rotatably mounted on closure means 185, can be raised or lowered.

At the lower end reaction tube 177 is connected in any suitable manner with efuent manifold 191. Thus, for example, the reaction tube 177 is provided with a hemispherical cap 189 preferably butt-Welded to the lower end of reaction tube 177. The cap 189 is provided with a port to which is welded tube eiuent conduit 190 which in turn is Welded to or otherwise mounted on reactor efliuent manifold 191, Reactor effluent manifold 191 is provided with a pipe 192 to which the associated elliuent manifold branch 33 or 34 or 35 or 36 is connected in any suitable manner (FIGURE 1).

A foraminous partition 193 is movably mounted in any suitable manner in the interior of reaction tube 17 7 near or at the junction of the reaction tube 177 with the cap 189. Preferably, a mass of inert particles, for example,

16 fused silica, corundum, or the like, preferably of graded sizes with the smallest pieces at the top rests upon foraminous partition 193 and acts to separate any particles of catalyst entrained in the reaction vapors from the reaction vapors before the latter enters eluent conduit 190.

The reactant vapors flow from the feed inlet manifold branch, for example 17 (FIGURE 1) to reactor inlet manifold 184, thence through tank manifold branch 183 to reaction tube inlet 182. The reaction vapors flow downwardly through reaction tube 177 to tube eflluent conduit 190, thence to reactor eiiiuent manifold 191, pipe 192 and outlet manifold branch 33, or 34, or 35, or 36.

The hot heat transfer medium (HTM) iows from HTM inlet manifold branch 127, 128, or 129, or to nozzle 166 in Venturi 165. The hot HTM and inducted recycle HTM ow through Venturi 16S at a high velocity of about 75 to about 150 feet per second into the chamber between plate and bottom 161 of the isothermal reactor. The HTM is forced upwardly through the annulus between the outer periphery of reaction tube 177 and the inner periphery of jacket 176 and flows out at the top of jacket 176. The HTM from the plurality of reaction tube-jacket assemblies forms a pool surrounding the assemblies the height of which in the reactor is regulated by float 194 in conjunction with one of the liquid-level controls 135, 136, 137, and 13S (FIG- URE 2). The HTM ows from the reactor pool of HTM through HTM outlet 164, by-pass 16S to Venturi 165, and via nipple 169 and return manifold branches 147, or 143, or 149, or 150.

A presently preferred form of a radiantly heated isothermal reactor is illustrated in FGURE 6. Itis preferred to use one of this type of radiantly heated isothermal reactors for each of the heat transfer medium reactors illustrated in FIGURES l, 2, 3, and 4.

The radiantly heated reactor shown in FIGURE 6 provides for heating the reaction tubes from two sides. A less desirable structure from the standpoint of ease of regulation of the temperature in the reaction tubes provides for heating the reaction tubes from only one side.

The presently preferred radiantly heated isothermal reactor comprises a base 400 of any suitable heat resistant material such as insulated steel supported on a plurality of pillars 402, A shell 403 of any suitable structural material such as steel is rigidly mounted on base 400. A furnace or heater throat 401 is rigidly supported by struts 405.

Spaced from shell 403 a heat resistant wall 406 is rigidly mounted on base 400. Wall 406 is provided with a plurality of radiant burners (not shown) for burning uid fuel, such as refinery gas, fluid petroleum fractions,

natural or producer gas, to provide radiant heat bathing reaction tubes 501 and others not shown. The construction of heat resistant wall 406 and the embeddedradiant heat burners together with the fuel mains, piping and controls to regulate the burners individually or in banks to control the heat supplied to various portions of the reaction tubes is well known, does not require description and are omitted from FIGURE 6 for simplicity.

Mounted rigidly upon base 400 and spaced apart from the innermost ring of reaction tubes is heat resistant arch 407 having an inner lining 404. Heat resistant arch 407 like heat resistant wall 406 is provided with a plurality of radiant burners. Heat resistant arch 407 and the associated burners are constructed in a well known manner. The piping and regulation valves whereby the radiant burners mounted in arch are supplied with fuel are omitted from FIGURE 6 for simplicity of illustration. The radiant burners in arch 407 are also provided with controls whereby the burners are regulated individually or in banks to control the heat supplied to various portions of the reaction tubes. The radiant burners associated with arch 407 are supplied with liquid or gaseous fuel similar to that supplied to the radiant burners associated with wall 406.

Rigidly mounted on arch 407 is annular metal pipe 408 having outer insulation 409. This construction provides an annular stack 410 between throat 404 and insulated pipe 408.

At a suitable distance above the plane of the top of -arch 407 heat reiiecting surfaces 411 constructed of irebricks and supported in any suitable manner are mounted to provide also a support for the reaction tubesl The reaction tubes are rigidly mounted in tube support plates 412 supported in any suitable manner. `Reiiecting surfaces 411 are tied in to the shell and supported in the usual manner.

The construction of the reaction tubes and the catalyst ycartridges is shown in greater detail in FIGURES 7 and 8 and described in conjunction therewith.

The radiantly heated isothermal reactor illustrated in FIGURE 6 is provided with at least one, and preferably two fluid reactant mains (not shown) from which the charge mixture flows through conduits 414 and 41S and others not shown to the interiors of the reaction tubes. The reaction tubes extend through base 400 and each is provided with effluent conduits of which four, to Wit:

.effluent conduits 416, 417, 418, and 419 are shown. The

vparts in each of the figures have been designated by the same number. The reaction tube and cartridge train 'illustrated in FIGURE 7 comprises an outer tube 501 having a high coeiiicient of heat transfer concomitant lwith structural strength and a minimum of deformation `at reaction temperature.

Welded or otherwise suitably mounted in a rigid manner at one end, designated the head end, is a reaction tube'head 502 having a throat 503, the inside diameter of which is substantially the same as that of the reaction tube 501. At a suitable distance above the throat the reaction tube head is provided with a laterally extending vapor inlet conduit 504. Above the vapor inlet conduit the inner cross-section of the reaction tube head is tapered to receive a frusto-conical plug 505. Frusto-conical plug 505 is provided with a substantially axial peg 506 provided at the free end with threads to receive nut 507. Annular plug S08 threaded to complement interior threads in the neck of reaction tube ,header 502l above the tapered plug section and having central port having substantially the same diameter as the outer diameter of axial peg 506 is turned into reaction tube head 502 to force frusto-conical plug 505 down into the tapered section of reaction tube head 502 by means of complementary projections of which four, to wit: S09, 510, 511, and 512 are shown therebymaking a gas-tight closure.

Eachreaction tube 501 is provided with a train of catalyst cartridgescomprising a head cartridge, a plurality of intermediate cartridges, and a tail cartridge. Except for minor details each of the cartridges is of the same general construction. That is to say, the upper plate of the head cartridge is provided with means which can be engaged by a hook or the like for inserting the cartridge train in, and removing the cartridge train from a reaction tube. The head cartridge and each of the intermediate cartridges in plane above the bottom annular plate thereof is provided with substantially fixed support means for supporting a coupling member which is free to oscillate or rotate in said support means. Each of the intermediate cartridges, and the tail cartridge in the plane below the upper annular plate thereof is provided with fixed coupling member receiving means in whichthe coupling 18 member of the immediately forward cartridge is free to oscillate or rotate but not disengage. The tail cartridge `has no fixed support means in the plane above the bottom annular plate.

In the drawing FIGURE 7 a reaction tube with a head cartridge, the upper portion of an intermediate cartridge, and the bottom portion of a tail cartridge of a cartridge train having a plurality of intermediate cartridges are shown.

In FIGURE 7A a means of supporting the tail cartridge and the other cartridges of train different from that shown in FIGURES 7 and 8 is illustrated. It will also be observed that the reaction tube in FIGURE 7A has no closure means similar to that illustrated in FIGURE 7.

The cartridge trains illustrated in FIGURES 7 and 8 differ primarily in that (l) the head cartridge in FIGURE 7 has an upper discoid plate whereas the head cartridge in FIGURE 8 has an upper annular plate; and (2) the bottom plate of the tail cartridge in FIGURE 8 rests upon and is supported by an inner iange or shoulder on the arc mounted on the outer surface of the bottom plate of vthe tail cartridge illustrated in FIGURE 8. Furthermore,

the Cartridge train illustrated in FIGURE 8 provides for initial flow of reactants from the central conduit through the upper annular catalyst bed to the annular space between the cartridge and the reaction tube whereas in FIGURE 7 the ow of reactants is the reverse of that -illustrated in FIGURE 8 as more fullydescribed here- 'inafteix A catalyst cartridge comprises an upper plate, a bottom plate, an intermediate vapor guiding plate, an outer foraminous cylinder, a first inner foraminous cylinder iixedly mounted between the aforesaid upper plate and the aforesaid intermediate plate, and a second inner foraminous cylinder ixedly mounted between the aforesaid intermeid-ate plate and the aforesaid bottom plate all of which are concentric. Thus, in the preferred construction, as illustrated in FIGURE 8, a head cartridge comprises upper annular plate 514 having an outside diameter to make a sliding fit with a reaction tube when cold and 'va-substantially vapor-tight tit with the reaction tube at ,annular plate 515 near the outer peripheries of the aforesaid annular plates 514 and 515. Arstfinner foraminous cylinder S17 is fixedly mounted between upper annular plate 514 and intermediate discoid plate 518, the inner periphery of upper annular plate S14 and the inner periphery of first foraminous cylinder 517 being substantially in the same vertical plane. Intermediate discoid plate 518 has a diameter about 75 to about 85 percent of the inner diameter of outer foraminous cylinder 516 and is concentric with iirst inner foraminous cylinder 517.

A second inner foraminous cylinder 519 is fixedly mounted between bottom annular plate 515 and intermediate discoid plate 518. The inner periphery of bottom annular plate 515 and the inner periphery of second inner foraminous cylinder 519 are in substantially the same vertical plane. The second inner foraminous cylinder 519 and intermediate discoid plate 518 are concentric. Thus, upper annular plate 514, intermediate discoid plate 518, bottom annular plate 515, outer foraminous cylinder 516, and inner foraminous cylinders 517 and 519 are substantially concentric and concentric with a reaction tube.

The headcartridge of the train is provided with a yoke or bail or other suitable means 520 rigidly mounted on upper annular plate 514, said yoke or other means being constructed and arranged to be engaged by a hook or the tube, the head cartridge, and subtended cartridge train.

The head cartridge and all intermediate Cartridges of a catalyst cartridge train are provided with means for oscillatory or rotary coupling of the cartridge to a succeeding cartridge. For example, in a plane vertically above the plane of bottom annular plate 515 a coupling support member comprising a collar 521 having lugs 522 at 180 degrees is xedly mounted horizontally on the inner periphery of second inner foraminous cylinder 519 concentric with bottom annular plate 515. The intermediate and tail catalyst cartridges are provided with means for oscillatory or rotary coupling of the catalyst cartridge to the preceding catalyst cartridge. Thus, the intermediate cartridge having upper annular plate 514 is provided with a coupling support member comprising a collar 523 having lugs 524 at 180` degrees is xedly mounted on the inner periphery of first foraminous cylinder 517 of the intermediate catalyst cartridge in a horizontal plane below the plane of upper annular plate 514 of the intermediate catalyst cartridge. A coupling member, for example, a bolt 525 having lock nuts 526 and 527 links each catalyst cartridge to the succeeding catalyst cartridge. Coupling member 525 is free to oscillate or rotate within collars 522 and 523.

The tail catalyst cartridge and the catalyst train are movably mounted on a ring or lugs 529, say four at 90 degrees, rigidly mounted contiguous to the lower end of reaction tube 501. The lower end of reaction tube 501 is mounted in any suitable manner, as by welding, to a reaction tube tail piece 539 similar in construction to header 502.

Tail piece 539 has a throat 540 the inside diameter of which is substantially the same as the inside diameter of reaction tube 561. At a suitable distance from the throat the reaction tube tail piece is provided with a laterally extending vapor outlet conduit 541. Intermediate to vapor outlet 541 and to the joint of tail piece 539 and reaction tube 501 the throat of tail piece 539 is provided with an external support ring 542 which is positioned on the reaction tube assembly to be embedded in the insulation of floor dit@ (FIGURE 6) of the reactor.

Intermediate to throat 546 and the free end of tail piece 539 the inner cross-section of the tail piece 539 is machined to receive a frustro-conical plug 543.

Frustro-conical plug 543 is provided with a substantially axial peg 544 having the free end threaded to receive nut 545. Annular screw plug 546 is threaded to complement the interior threads in the neck 547 of tail piece 539 external of the tapered portion of the tail piece. Annular screw plug 546 has an inner diameter substantially that of the outer diameter of peg 544 and makes a sliding t therewith. Frustro-conical plug 543 is provided with a plurality, eg., two, projections 548 and 549. Annular screw plug 546 is provided with complementary projections 55% and 551.

Frustro-conical plug 543 is placed in the tapered portion of tail piece 539, annular screw-plug 546 is turned in to force frustro-conical plug into the tapered section of tail piece 539 by means of complementary pairs of projections 548 and 55@ and 549 and 551 to provide a closure which is reactant-tight. Nut 545 is then turned in on peg 544 to hold frustro-conical plug 543 and annular screw plug 546 in place and provide a secured reactant-tight closure of the reaction tube and reaction tube tail piece.

In this preferred structure (FIGURE 8) the flow of reactant vapors is as follows: From throat 503 the reactant vapors How into central conduit 552 formed by the first inner foraminous cylinder. Conduit 552 is closed by intermediate discoid plate 518. Therefore, the reactant vapors flow from conduit 552 through iirst inner foraminous cylinder 517, through the annular bed of catalyst coniined vertically between iirst inner foraminous cylinder 517 and outer foraminous cylinder 516, and through outer foraminous cylinder 516 into the annular space 553 between outer foraminous cylinder 516 and reaction tube 501. The reactant vapors flow downwardly in the annular space 553 past the plane of intermediate discoid plate 518 through the outer foraminous cylinder 516, the annular catalyst bed vertically confined between outer foraminous cylinder 516 and second inner foraminous cylinder 519 and through second foraminous inner cylinder 519 into central conduit 554 formed by the second inner foraminous cylinder. Bottom plate 515 being annular the reactant vapors iiow from conduit 554 of the head catalyst cartridge into the central conduit 555 of the iirst intermediate catalyst cartridge. The flow of reactant vapors in the intermediate cartridges is from the central conduit of the upper section to the annulus, back to the central conduit of the second section and to the succeeding cartridge as described in conjunction with the description of the head cartridge. From the central conduit of the last intermediate catalyst cartridge the reactant vapors flow into the central conduit of the upper section of the tail cartridge to the annulus and back to the central conduit 556 of the second section of the tail cartridge. From the central conduit 556 of the second section of the tail catalyst cartridge the reactant vapors flow through the port of annular bottom plate 515 of the tail catalyst cartridge into the throat 540 of the tail piece 539 of the reaction tube. From throat 54@ the reactant vapors ilow to and through vapor outlet 541 to an outlet manifold branch, eg., 417 and manifold 426 (FIGURE `6) and thence through outlet 421 to an adiabatic reactor, e.g., 26 (FIGURE `1) or 358 (FIGURE 3).

The catalyst cartridges can be constructed as illustrated in FIGURE 7 to provide for iiow of reactant vapors from the throat 5tl3 of the head of a reaction tube 501 around discoid upper plate 557 into the annular space between the outer foraminous cylinder 516 and reaction tube 501 through the annular catalyst bed vertically confined between outer foraminous cylinder 516 and first inner foramnous cylinder 517, and through iirst inner foraminous cylinder 517 into central conduit 552. From central conduit 552 of the first section of the head catalyst cartridge the reactant vapors flow through the port of the intermediate annular plate 558 into central conduit 554 of the second section of the head catalyst cartridge. From central conduit 554 the reactant vapors flow through second inner foraminous cylinder 519, through the annular bed of catalyst vertically confined between second inner foraminous cylinder 519 and outer foraminous cylinder 516 into the annular space between reaction tube 501 and outer foraminous cylinder 516. The reactant vapors ilow downwardly through the aforesaid annular space below the plane of discoid bottom plate 559 and upper discoid plate 560 of the first intermediate cartridge into the annular space between reaction tube 5M and outer foraminous cylinder 561 of the rst intermediate cartridge. The flow of reactant vapors in the first and succeeding intermediate cartridges and in the tail catalyst cartridge of the train is as described in conjunction with the head catalyst cartridge of the train.

In the embodiment of the catalyst cartridge in which the flow of reactant vapors is from the annular space between the outer foraminous cylinder and the react-ion tube to the central `conduit of the upper section of the cartridge and from the central conduit of the upper section of the cartridge to the central conduit `of the second section of the cartridge and thence to the annular space between the outer foraminous cylinder and the reaction tube the `structure of the catalyst cartridges differs from that illustrated iin FIGURE 8 and described hereinbefore in that the upper and bottom plates 'are discoid rather than annular and the intermediate vapor guiding plate is annular rather than discoid. Thus, in FIGURE 7 upper plate 557 is discoid having a diameter `when `at reaction temperature less than the inner diameter of reaction tube 50d to provide an annular passage Ifor reactant vapors. Bottom plate 559' likewise is discoid and has a diameter fwhen at reaction temperature less than the inner diameter 21 of reaction tube v501 to provide an annular passage for reactant vapors.

Intermediate vapor guiding plate 558 is annular having an inner di-ameter substantially that of the ii-rst and second inner ioraminous cylinders and an outer diameter substantially that of the inner diameter of the outer foraminous cylinder. Alternatively, outer foraminouscylinder 516 can be in an upper section and a lower section in which construction intermediate annular vapor lguiding plate 558 has Aan outside diameter substantially equal to the inner diameter of the reaction tube -at reaction temperature.

The cartridges are provided with coupling supports such as illustrated in FIGURE 8.

On the other hand, bottom discoid plate 559 (FIGURE 7) can be provided with a coupling pin or bolt port providing la sliding tit with the shank of the coupling pin or bolt. `|[The head of the coupling pin or bolt resting on the discoid plate 559 when the train is freely suspended but being spaced from discoid plate 559 when the train is mounted in a reaction tube] 'Ihe intermed-iate and tail cartridge cases are provided with a coupling pin or bolt receiving member 562 `and an internally threaded nut 563 rigidly mounted on receiving member 562 into which coupling pin or bolt 525 is turned sufficiently to secure the cartridge to the coupling pin or bolt.

It is to be observed that in both embodiments of the cartridge train it is preferred that there be some distance between :adjacent catalyst cartridges when the train is freely suspended but that each cartridge rests on the one immediately below when the train is positioned in a reaction tube.

Upper plate 557 of the head cartridge (FIGURE 7) is provided with means such as rod 564 mounted for rotary or oscillatory movement about the vertical axis of rod 564 in upper plate 557 and provided at the free end with a hook or eye engageable by an eye or hook 565 rigidly mounted on the under side of frustro-conical plug 505.

In FIGURE 8 the bottom annular 515- of the tail cartridge of the catalyst cartridge train rests on and is supported by shoulder or ring 529. When positioned in the reaction tube the head .and intermediate cartridges rest upon and are supported by the tail cartridge.

Eln FIGURE 7 the tail cartridge is movably mounted or rest-s upon a plurality of legs 567 which are krigidly mounted on plate 568 which is rigidly mounted on frustoconical plug 543.

In FIGURE 7A .the tail cartridge is movably mounted or rests on a plurality of legs 569 which yare rigidly mounted on ring 571 rigidly mounted on shoulder 574. A preferable construction for the tail piece of the reaction tube illustrated in FIGURE 7A is to mount a reducer'having a shoulder 574 on the tail portion of reaction tube 501 and to rigidly mount anelbow 573 yon the free end of reducer 574. The elbow being in'turn connected in a reaction products-tight manner with the isothermal efiiuent manifold, e.g., 420 (FIGURE 6).

It will be observed that with each cartridge train the flow of reactant vapors is through the annular catalyst beds either from the outer ioraminous cylinder to the inner toraminous cylinder or vice versa. When the reactant vapors are in the -annular space between the outer foraminous cylinder yand the reaction tube the temperature of the vapors is raised by contact with the heated reaction tube. In this manner the heat of endothermic reaction lost in passage through the -annular bed isrestored and a high degree of isotherrnicity is obtained.

Those skilled in the art will recognize that the present invention in its preferred embodiment provides for a plurality of reaction tubes in which the flow of reactant vapors is from a central passage through an annular catalyst bed to a reheating annulus and from the reheating annulus through an annular catalyst bed to a central conduit of each of a plurality of catalyst cartridges of a cartridge train and from the central conduit of the train Ato the flow of reactaut vapors is from a reheating -annulus through an annular catalyst bed to a central conduit and -4from the central conduit through `an annular catalyst bed toa reheating annulus of each of a plurality of catalyst cartridges in Ia cartridge train and from the reheating annulus of the tail cartridge or" the train to the rvapor out- 'let of the reaction tube.

We claim:

fl. Inithe method of catalytic hydrocarbon conversion wherein .a closed container a plurality of vertical tubu- -lar reaction zones are established, wherein in each oi said tubular reaction zones .a single columnar static bed of particle-form solid hydrocarbon conversion catalyst, hereinafter designated catalyst, is established, wherein the preponderant portion of each of said tubular yreaction zones within said closed container is in direct heat exchange relation with heat transfer medium, wherein the total periphery of each of said single columnar static beds of catalyst is in contact with the wall of said tubular reaction zone .and thus each said single columnar Astatic bed off catalyst is in indirect heat exchange relation throughout the entire length thereof with said heat transier medium, wherein a substantially equal volume of .charge mixture comprising uaporous hydrocarbon re- -actant'is introduced into each of `said tubular reaction `zones, wherein said charge mixture llows downwardly mthrongh said single columnar static bed of catalyst in each oi said reaction tubes without substantial indirect heat transfer relation with said heat transfer medium, and wherein Ithe effluents of said plurality of vertical reaction zones lare combined to iorm feed for .a single adiabatic reaction zone, the improvement which comprises in each oi the aforesaid vertical reaction Zones establishing a plurality of annular major static beds of said .catalyst comprising a head annular major catalyst bed, at least one intermediate annular major catalyst bed, land a vtail annular major catalyst bed, the outer peripheries of all of sai-d lannular major static catalyst beds being spaced from the inner peripheries oi said tubular reaction tubes to :form outer vapor pathways between theouter peripheries of said major catalyst beds and the inner periphery of said reaction zone for vaporous charge mixture, each of said annular major catalyst beds being divided horizontally into an upper umido-r annular catalyst bed and a lower minor annular catalyst bed, the inner periphery o-f each or said annular minor catalyst beds lforming an inner Vapor pathway for vaporous charge mixture, each lof said minor annular catalyst beds being in vaporous communication with contiguous minor annular catalyst beds for substantially lateral ilow of lvaiporous charge mixture alternately between said outer vapor pathway and said inner vapor pathway 'and flowing said charge mixture laterally through .said minor annular bed-s of catalyst alternately in one direction land then in the opposite direction, and heating said yaporous charge mixture by indirect heat exchange with said heat transfer medium whilst said charge mixture is flowing through each of said outervapor pathways.

2. The method of catalytic hydrocarbon conversion as Set forth and described in claim l wherein the hydrocarbon conversion catalyst in the isothermal reaction zones has hydrogenating land hydrocracking capabilities.

3. The method of catalytic hydrocarbon conversion as setdorth and described in claim l wherein the hydrocarbon conversion catalyst in the isothermal reaction zones Aand wherein the hydrocarbon conversion catalyst conftacted under adiabatic conditions larereforming catalysts.

4. The method of catalytic hydrocarbon conversion as set forth and `described in claim l wherein the catalyst in leach minor annular bed is 1a mixture of at least two catalysts, one of which catalyzes one hydrocarbon reac- 23 tion and the other of which catalyzes a second hydrocarbon reaction.

I5. The method of catalytic hydrocarbon conversion as set :forth and described in claim 1 wherein the hydrocarbon reactant boils in fthe naphtha boiling range and comprises parains and naphthenes, wherein the hydrocarbon conversion catalyst in the tubular reaction Zones comprises platinum-group metal reforming catalyst and wherein ,the lhydrocarbon conversion catalyst in the adiabatic reaction zones comprises non-noble metal reforming catalyst.

6. The method of catalytic hydrocarbon conversion as se-t forth in claim 1 wherein .the flow of charge mixture in the upper annular bed cf catalyst in head annular major bed of catalyst is substantially Ifrom the inner vapor pathway thereof to the outer vapor pathway.

7. 'Ilhe method of catalytic hydrocarbon conversion as set forth in claim 1 wherein the vaporous hydrocarbon reactant comprises petroleum naphtha and Athe catalyst in at least said annular major catalyst beds is platinumgroup metal reforming catalyst comprising about 0.35 to 0.6 percent by weight of platinum on alumina support.

8. The method of catalytic hydrocarbon conversion as set forth in claim l wherein the catalyst in each minor bed is intimately mixed with an amount of reaction inert particle-form solid material to provide a `substantially constan-t difference in temperature between the reactant vapors entering a mino-r annular catalyst bed and leaving said minor catalyst bed.

9. A reaction tube for catalytic conversion Iwhich comprises a cylindrical tube of substantially uniform internal diameter having a length several multiples yof the diameter thereof, a vapor inlet in the region of the head end of the tube, a vapor-tight movable closure means in said tube at -the end contiguous to the aforesaid vapor inlet, a vapor outlet in lthe region of the tail end of the aforesaid tube, a second vapor-tight movable closure means in said tube at the end contiguous to said Vapor outlet, catalyst cartridge `train supporting means mounted on the inner periphery of said reaction tube vertically spaced inwardly from said vapor outlet constructed and arranged rto support a catalyst cartridge train comprising a head cartridge, `at least one intermediate cartridge, and a tail cartridge, each cartridge of said catalyst cartridge train comprising -a first plate, a second plate, and a third plate, a first `ou-ter yforaminous cylinder mounted between said first plate and said second plate, a first inner foral-minous cylinder mounted between said first plate and said second plate and spaced inwardly @trom said first outer ttorarninous cylinder to provide for a first annular static bed of particle-form solid catalytic material between said first plate and said second plate, a second outer foraminous cylinder mounted between said second plate .and said third plate, a second inner ioraminous cylinder mounted between said second plate and said third plate and spaced inwardly from said second outer foraminous cylinder to provide for :a second annular static bed ci particle-form solid catalytic material between said second plate and said third plate, means mounted in the rst plate of the laforesaid head catalyst cartridge constructed and arranged for suspending said head cartridge and subtended cartridge train therefrom, means mounted in the said Ithird plate of each catalyst cartridge other than the tail catalyst cartridge constructed and arranged for movably suspending a catalyst cartridge, the third plate of the aforesaid tail catalyst cartridge being constructed and arranged yto be movably mounted on the aforesaid catalyst train supporting means, each of said catalyst cartridges being arranged for lateral flow of reactant vapors in one direction through the first static annular bed of particle-(form solid catalytic material and for lateral flow in the other direction through the second static bed of lparticle-form solid catalytic material to provide in ccnjunction with the inner periphery of the aforesaid reaction tube contact of rea-etant vapors in annular dow Iwith said inner periphery of said reaction tube to provide heat exchange between said reaction tube and said reactant vapors prior to passage through the subsequent static annular bed of particle-form solid catalytic material.

l0. A catalyst cartridge comprising a plurality of endto-end annular static beds of particle-form solid catalytic material, each static bed of particle-form solid catalytic material being confined between two spaced apart plates and between an outer forarninous cylinder and an inner lforaminous cylinder providing a central conduit, said catalyst cartridge being constructed and arranged in cooper-ation with the inner periphery of a reaction tube to iorm outer annuli between the outer peripheries of said annular static beds yof catalytic material and said inner periphery of said tubular reaction zone for flow of reactants substantially laterally alternately in one direction through one annular static bed of particle-form solid catalytic material and substantially laterally in the other direction through the next in line annular static bed of particle-form solid catalytic material, and to provide heat exchange between reactant vapors flowing through said outer annuli and the inner periphery of the aforesaid reaction tube.

11. A catalyst, cartridge as set forth and described in claim 10 having at one end means for receiving and holding in a sliding rotatable manner' catalyst cartridge coupling means.

12. A catalyst cartridge as set forth and described in claim 1() having at one end coupling support means constructed and arranged 4to suspend in a sliding :and rotatable manner catalyst cartridge linking means.

13. A catalyst cartridge as set -forth and described in claim 10 having at one end coupling support means constructed and arranged to suspend in a sliding and'rotatable manner catalyst cartridge coupling means and having at the other end means `for receiving and holding in a sliding rotatable manner catalyst cartridge coupling means.

14. An intermediate catalyst cartridge comprising an upper plate, a lower plate, and an intermediate pla-te, an outer foraminous cylinder rigidly mounted between said upper and lower plates, a first inner foraminous cylinder rigidly mounted between said upper and intermediate plates, a second inner foramino-us cylinder rigidly mounted between said intermediate and bottom plates, all of said plates `and foraminous cylinders being concentric, a first annular bed of particle-form solid hydrocarbon conversion catalyst confined between said upper and intermediate plates between said outer foraminous cylinder and said first inner -foraminous cylinder, a second annular bed of particle-form solid hydrocarbon conversion catalyst confined between said intermediate and bottom plates between said outer foraminous cylinder and said second inner foraminous cylinder, mean-s for slidably connecting said catalyst cartridge to a preceding catalyst cartridge, andmeans for slidably connecting said catalyst cartridge to :a succeeding catalyst cartridge, said intermediate catalyst cartridge being constructed and arranged in conjunction with a reaction tube to provide a sinuous reaction path having a plurality of portions Vthereof in indirect heat exchange relation through said reaction tube with heat transfer medium.

l5. A head catalyst cartridge comprising an upper plate, a lower plate, and an intermediate plate, an outer foraminous cylinder mounted between said upper and lower plates, a first inner foraminous cylinder rigidly mounted between said upper and intermediate plates, a second inner foraminous cylinder rigidly mounted between said intermediate and bottom plates, allof said plates and foraminous cylinders being concentric, a first `annular bed of particle-form solid hydrocarbon conversion catalyst ccnned between said upper and intermediate plates between said outer fo-rarninous cylinder 4and said first inner forarninous cylinder, a second annular bed of particle-form solid hydrocarbon conversion catalyst confined between said intermediate and bottom plates between said outer foraminous cylinder and said second inner foraminous cylinder, means mounted on said upper plate for suspending said head cartridge, and means for slidably connecting said head cartridge to an intermediate cartridge, said head catalyst cartridge being constructed and arranged in conjunction with a reaction tube to provide a sinuous reaction path having a plurality of portions thereof in indirect heat relation through said reaction tube with heat transfer medium.

16.l A tail catalyst cartridge comprising an upper plate, a lower plate, and an intermediate plate, an outer forarninous cylinder mounted between said upper and lower plates, a iirst inner -foraminous cylinder rigidly mounted between said upper and intermediate plates, a second inner foraminou-s cylinder rigidly mounted between said intermediate and bottom plates, all `of said plates and foraminous cylinders bei-ng concentric, a rst annular bed of particle-form solid hydrocarbon conversion catalyst confined between said upper and intermediate plates between said outer fonaminous cylinder and said rst inner foraminous cylinder, a second annular bed of particleform sol-id hydrocarbon conversion catalyst conned between sa-id intermedi-ate and bottom plates between said outer foraminous cylinder and said second inner foraiminous cylinder, means mounted on said upper plate for slidably connecting said tail cartridge to a preceding intermedi-ate cartridge, said tail cartridge being constructed and arranged in conjunction with a reaction tube to provide a sinuous reaction path having a plurality of portions thereof 4in indirect heat transfer relation through said reaction tu'be with heat transfer medium.

17. A reaction tube for catalytic conversion which comprises a cylindrical tube of substantially uniform intern-a1 diameter having a length at least several multiples of the diameter thereof, a vapor inlet in the region of the lhead of said reaction tube, a vapor outlet in the region of the opposite tail end of s-aid reaction tube, catalyst train supporting me-ans rigidly mounted in the region of the outlet of said reaction tube constructed and arranged to support a catalyst cartridge train, and movable vapor-tight closure means at the head end of said reaction tube constructed .and arranged when open for introducing and removing said catalyst cartridge train.

18. The reaction tube `set forth in claim 17 wherein the catalyst train support-ing means is a ring rigidly mounted on the inner periphery of said reaction tube inwardly from said vapor outlet.

19. The reaction tube `set forth in claim 17 wherein said reaction tube is provided with a second movable, vaportight closure rne'an-s, and catalyst train support means rigidly mounted on said closure means, said catalyst train support means comprising a plurality of legs rigidly mounted on the inner surface of said closure means.

20. A catalyst cartridge train comprising a head catalyst cartridge as set forth in claim 15, coupled to an intermediate catalyst cartridge as set forth in claim 14 coupled toa tail catalyst cartridge as set yforth in claim 16.

21. The combination of a reaction tube and the catalyst cartridge train as `set forth in claim 20.

References Cited in the le of this patent UNITED STATES PATENTS 2,443,673 AtWell June 22, 1948 2,516,943 Barber Aug. 1, 1950 2,518,583 Watson Aug. 15, 1950 2,638,407 Steeves May 12, 1953 2,755,230 Guernsey Iuly 17, 1956 2,886,507 Elliott et al. May 12, 1959 2,910,431 Sage et al Oct. 27, 1959 2.943.998 Decker July 5, 1960 

1. IN THE METHOD OF CATALYTIC HYDROCARBON CONVERSION WHEREIN IN A CLOSED CONTAINER A PLURALITY OF VERTICAL TUBULAR REACTION ZONES ARE ESTABLISHED, WHEREIN IN EACH OF SAID TUBULAR REACTION ZONES A SINGLE COLUMNAR STATIC BED OF PARTICLE-FORM SOLIDS HYDROCARBON CONVERSION CATALYST, HEREINAFTER DESIGNATED CATALYST, IS ESTABLISHED, WHEREIN THE PREPONDERANT PORTION OF EACH OF SAID TUBULAR REACTION ZONES WITHIN SAID CLOSED CONTAINER IS IN DIRECT HEAT EXCHANGE RELATION WITH HEAT TRANSFER MEDIUM, WHEREIN THE TOTAL PERIPHERY OF EACH OF SAID SINGLE COLUMNAR STATIC BEDS OF CATALYST IS IN CONTACT WITH THE WALL OF SAID TUBULAR REACTION ZONE AND THUS EACH SAID SINGLE COLUMNAR STATIC BED OF CATALYST IS IN INDIRECT HEAT EXCHANGE RELATION THROUGHOUT THE ENTIRE LENGTH THEREOF WITH SAID HEAT TRANSFER MEDIUM, WHEREIN A SUBSTANTIALLY EQUAL VOLUME OF CHARGE MIXTURE COMPRISING VAPOROUS HYDROCARBON REACTANT IS INTRODUCED INTO EACH OF SAID TUBULAR REACTION ZONES, WHEREIN SAID CHARGE MIXTURE FLOWS DOWNWARLDY THROUGH SAID SINGLE COLUMNAR STATIC BED OF CATALYST IN EACH OF SAID REACTION TUBES WITHOUT SUBSTANTIAL INDIRECT HEAT TRANSFER RELATION WITH SAID HEAT TRANSFER MEDIUM, AND WHEREIN THE EFFLUENTS OF SAID PLURALITY OF VERTICAL REACTION ZONES ARE COMBINED TO FORM FEED FOR A SINGLE ADIABATIC REACTION ZONE, THE IMPROVEMENT WHICH COMPRISES IN EACH OF THE AFORESAID VERTICAL REACTION ZONES ESTABLISHING A PLURALITY OF ANNULAR MAJOR STATIC BEDS OF SAID CATALYST COMPRISING A HEAD ANNULAR MAJOR CATALYST BED, AT LEAST ONE INTERMEDIATE ANNULAR MAJOR CATALYST BED, AND A TAIL ANNULAR MAJOR CATALYST BED, THE OUTER PERIPHERIES OF ALL OF SAID ANNULAR MAJOR STATIC CATALYST BEDS BEING SPACED FROM THE INNER PERIPHERIES OF SAID TUBULAR REACTION TUBES TO FORM OUTER VAPOR PATHWAYS BETWEEN THE OUTER PERIPHERIES OF SAID MAJOR CATALYST BEDS AND THE INNER PERIPHERY OF SAID REACTION ZONE FOR VAPOROUS CHARGE MIXTURE, EACH OF SAID ANNULAR MAJOR CATALYST BEDS BEING DIVIDED HORIZONTALLY INTO AN UPPER MINOR ANNULAR CATALYST BED AND A LOWER MINOR ANNULAR CATALYST BED, THE INNER PERIPHERY OF EACH OF SAID ANNULAR MINOR CATALYST BEDS FORMING AN INNER VAPOR PATHWAY FOR VAPOROUS CHARGE MIXTURE, EACH OF SAID MINOR ANNULAR CATALYST BEDS BEING IN VARPOROUS COMMUNICATION WITH CONTIGUOUS MINOR ANNULAR CATALYST BEDS FOR SUBSTANTIALLY LATERAL FLOW OF VAPOROUS CHARGE MIXTURE ALTERNATELY BETWEEN SAID OUTER VAPOR PATHWAY AND SAID INNER VAPOR PATHWAY AND FLOWING SAID CHARGE MIXTURE LATERALLY THROUGH SAID MINOR ANNULAR BEDS OF CATALYST ALTERNATELY IN ONE DIRECTION AND THEN IN THE OPPOSITE DIRECTION, AND HEATING SAID VAPOROUS CHARGE MIXTURE BY INDIRECT HEAT EXCHANGE WITH SAID HEAT TRANSFER MEDIUM WHILST SAID CHARGE MIXTURE IS FLOWING THROUGH EACH OF SAID OUTER VAPOR PATHWAYS.
 5. THE METHOD OF CATALYTIC HYDROCARBON CONVERSION AS SET FORTH AND DESCRIBED IN CLAIM 1 WHEREIN THE HYDROCARBON REACTANT BOILS IN THE NAPHTHA BOILING RANGE AND COMPRISES PARAFFINS AND NAPHTHENES, WHEREIN THE HYDROCARBON CONVERSION CATALYST IN THE TUBULAR REACTION ZONES COMPRISES PLATINUM-GROUP METAL REFORMING CATALYST AND WHEREIN THE HYDROCARBON CONVERSION CATALYST IN THE ADIABATIC REACTION ZONES COMPRISES NON-NOBLE METAL REFORMING CATALYST. 